The proposed research will examine the role of somatosensory inputs associated with facial skin deformation in speech perception and speech motor learning. The role of these inputs is poorly understood yet clearly important for speech control since a number of articulatory muscles lack traditional muscle proprioceptors (muscle spindles and tendon organs). The principal goal is to document somatosensory involvement in perception and speech learning. This goal will be accomplished by using a computer controlled robotic device to precisely deform the facial skin and by examining the resulting changes in speech motor output and speech perception. The proposed studies have two specific aims. The first aim is to document a bi-directional interaction of the somatosensory and auditory systems in speech processing. The second is to understand how somatosensory afferent inputs contribute to speech motor learning and more specifically, to test the idea that motor learning occurs in response to the modulation of somatosensory afferent input. Relevance: These studies have potential clinical applicability as well as contributing to our basic understanding of the mechanisms of speech motor control and speech perception. The investigation of the bi-directional interaction of the somatosensory and auditory systems should be helpful in understanding the sensory support for speech training and rehabilitation and in establishing the role of somatosensory afferents in speech leaning.